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Layered Double Hydroxides Decorated Graphic Carbon Nitride Film as Efficient Photoanodes for Photoelectrochemical Water Splitting
摘要： In the present work, we investigate the graphic carbon nitride (g-CN) film as photoanode to catalyze the photoelectrochemical (PEC) water oxidation and study the influence of NiCo layered double hydroxides (NiCo-LDH) layer on the performance. The g-CN film with good quality and intimate contact with substrate was in-situ prepared via solvothermal process and subsequent calcination. NiCo-LDH is further decorated on the g-CN film through cathodic electrochemical deposition to work as co-catalyst. The g-CN/NiCo-LDH composite with optimized NiCo-LDH loading amount exhibits a photocurrent of 11.8 μA cm-2 at 0.6 V vs. SCE, which is 2.8 times of bare g-CN. Characterizations and performance tests demonstrate that NiCo-LDH promoted reaction kinetics and charge separation. The results provide an effective strategy to improve the photoelectrochemical water oxidation performance of g-CN through NiCo-LDH co-catalyst. This work to investigate the photoelectrochemical water oxidation is of great significance toward explore the overall water splitting on the g-CN film.
关键词： Layered double hydroxides,Solvothermal process,Photoelectrochemical water oxidation,Co-catalyst,Graphitic carbon nitride
更新于2025-09-23 15:22:29
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Acid-treated Ti4+ doped hematite photoanode for efficient solar water oxidation—Insight into surface states and charge separation
摘要： Acid-treatment has been proved to be an efficient approach to improve the photoelectrochemical (PEC) performance of hematite. However, efforts to optimize hematite photoanode have been limited by an inadequate understanding of the semiconductor surface. Here we make efforts to understand the microscopic charge separation processes of Ti4+ doped Fe2O3 photoanode before and after acid-treatment. Surface photovoltage (SPV) transient and the work function measurements directly reveal that acid-treatment leads to passivation of the surface states. Surface photovoltage (SPV) spectroscopic studies coupled to open-circuit photovoltage (OPV) measurements indicate that the surface states of hematite photoanode before acid-treatment result in the pinning of the Fermi level, which reduce the intensity of interfacial electric field at the semiconductor-electrolyte interface.
关键词： Water oxidation,Charge separation,Surface states,Hematite,Acid-treatment
更新于2025-09-23 15:22:29
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A Noble-Metal-Free Heterogeneous Photosensitizer-Relay-Catalyst Triad Catalyzes Water Oxidation under Visible Light
摘要： An entirely earth abundant chromophore-relay-water oxidation catalyst triad system, which is robust and efficient at neutral pH, is presented. The synthesis involves the coordination of a porphyrin derivative to a bridging Fe(CN)5 group, which is then reacted with Co ions to prepare a covalently linked chromophore-Prussian blue analogue assembly. Light driven water oxidation studies in the presence of an electron scavenger indicate that the triad is active and it maintains a steady activity for at least 3 hours. Transient absorption experiments and computational studies reveal that the Fe(CN)5 group is more than a linker as it takes part in electron-transfer and co-operates with porphyrin in the charge separation process.
关键词： water splitting,triad,dye-sensitized,water oxidation,Prussian blue,porphyrin
更新于2025-09-23 15:21:01
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Selective Activation of Benzyl Alcohol Coupled with Photoelectrochemical Water Oxidation via a Radical Relay Strategy
摘要： Selective oxidation to produce target chemicals usually need activation of O2 at high temperature and/or pressure, which have largely restricted its practical operation and application. Here, we put forward a radical-relay strategy coupling photoelectrochemical (PEC) water oxidation towards efficiently selective conversion of benzyl alcohol (BA) to benzaldehyde (BAD). An illuminated BiVO4 (BVO) photoanode covered with an ultrathin (~3 nm) hydrothermally synthesized layered double hydroxide (U-LDH) catalyst and graphene (G) exhibited >99% selectivity to BAD (1.2 V vs. RHE). Mechanistic studies and DFT calculation verified that the hydroxyl radicals (?OH) generated from the oxidation of water are bound to the surface of U-LDH through hydrogen-bonding interactions and the energy is lowered. Fourier transform infrared spectroscopy showed that BA is adsorbed to the U-LDH catalyst, but BAD is not. Thus, the selectivity is not only favored by the controlled oxidation capacity of ?OH radicals, but the desorption of the desired product from the catalyst before further oxidation occurs. This work introduces an alternative PEC way to achieve mild and selective oxidation of BA derivatives based on ternary G@U-LDH@BVO catalysts.
关键词： radical relay,ultrathin LDH,aromatic alcohols,PEC water oxidation,selective activation
更新于2025-09-23 15:21:01
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Ti, Zn co-doped hematite photoanode for solar driven photoelectrochemical water oxidation
摘要： Although there have been many reports of metal doping to ameliorate the drawbacks of hematite as the photoanode for water oxidation, most of them focused on monometallic doping, and only a few of them payed attention to bimetallic doping. What is worse, the synergetic mechanism between two metal dopants was not su?ciently studied, especially the density functional theory (DFT) calculation. In this work, the n-type hematite was synthesized by introducing Ti dopant into hematite through the hydrothermal method, and dipping-sintering treatment was employed to further introduce homogeneously dispersed Zn dopant into that, forming the Ti, Zn co-doped hematite. Under the optimal condition, Ti-doped hematite photoanode reached approximately 2-times enhancement of the photocurrent density compared with the pristine one at 1.23 V vs. RHE, while Ti, Zn co-doped hematite anode obtained another 25% elevation. UV –Vis spectroscopy, Mott –Schottky plots, EIS analysis, photo-oxidation of hole scavenger (H 2 O 2 ), and DFT calculation were employed to understand the role of Ti, Zn dopant. Based on the obtained results, the synergetic mechanism of two dopants was discussed, i.e., the improvement of PEC performance of Ti, Zn co-doped hematite photoanode was possibly attributed to greater carrier density and improved charge separation e?ciency at the surface of hematite. This work provides new strategy and understanding of the improvement of PEC performance of hematite by doping engineering.
关键词： Photoelectrochemical water oxidation,Zn co-doping,Ti,DFT calculation,Hematite
更新于2025-09-23 15:21:01
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Design of an inherently-stable water oxidation catalyst
摘要： While molecular water-oxidation catalysts are remarkably rapid, oxidative and hydrolytic processes in water can convert their active transition metals to colloidal metal oxides or hydroxides that, while quite reactive, are insoluble or susceptible to precipitation. In response, we propose using oxidatively-inert ligands to harness the metal oxides themselves. This approach is demonstrated by covalently attaching entirely inorganic oxo-donor ligands (polyoxometalates) to 3-nm hematite cores, giving soluble anionic structures, highly resistant to aggregation, yet thermodynamically stable to oxidation and hydrolysis. Using orthoperiodate (at pH 8), and no added photosensitizers, the hematite-core complex catalyzes visible-light driven water oxidation for seven days (7600 turnovers) with no decrease in activity, far exceeding the documented lifetimes of molecular catalysts under turnover conditions in water. As such, a fundamental limitation of molecular complexes is entirely bypassed by using coordination chemistry to harness a transition-metal oxide as the reactive center of an inherently stable, homogeneous water-oxidation catalyst.
关键词： visible-light driven,hematite,polyoxometalates,water oxidation,catalyst
更新于2025-09-23 15:21:01
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Shape-dependent activity of anisotropic Ag nanostructures supported on TiO2 for the photoelectrocatalytic water oxidation
摘要： Herein, we report shape-dependent photoelectrocatalytic activity of Ag/Ag2O nanostructures supported on pristine or nitrogen-doped TiO2 (NTiO2). Isotropic (spherical) and anisotropic (cubic and triangular) nanocrystals of Ag/Ag2O nanocrystals were fabricated using complexing and surface directing agents. Microscopic images confirmed the formation of nanospheres (～ 50–60 nm), nanocubes (～ 50–70 nm), triangular nanoplates (～ 40–60 nm). The X-ray photoelectron spectroscopy indicated the presence of metallic silver (Ag0) and oxidized silver (Ag+). The as-prepared photoelectrodes were illuminated by Ultraviolet–Visible (λ = 300–600 nm) or visible radiations (λ = > 420 nm), and photoelectrochemical oxidation of water was examined. The findings indicate a significant correlation in the shape of Ag/Ag2O nanostructures, the incident wavelength, and the photoelectrochemical performance. In addition, different performance trend was discerned under Ultraviolet–Visible and visible excitations with respect to the amount of deposited Ag/Ag2O. The variation in activity observed with different shapes of Ag/Ag2O was correlated to enhanced optical property, arising due to the anisotropic structure, and electrical conductivity.
关键词： Photoelectrocatalytic activity,NTiO2,Water oxidation,Shape-dependent,Ag/Ag2O nanostructures,TiO2
更新于2025-09-23 15:21:01
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Compositionally graded SnO2/TiO2 bi-layered compounds with dramatically enhanced charge transport efficiency for self-driven water purification applications
摘要： To maximize the advantages of thin-film-based TiO2 photoelectrodes for transparent self-driven photoelectrochemical (PEC) reactions, we artificially designed a compositionally graded bi-layer compounds consisting of SnO2 and TiO2. This structure exhibited a vigorous photocatalytic activity, sufficient photovoltage, and long-term stability. A compositionally graded SnO2/TiO2 interface (G-SnTiO) for improved charge transport efficiency and sufficient photovoltage was derived by a solution process using simultaneous sintering after sol-gel coating the SnO2/TiO2 layers; the structure was verified by various analysis methods, such as transmission electron microscopy, energy dispersive X-ray spectroscopy, and secondary ion mass spectrometry. The high performance from the G-SnTiO structure was attributed to an effective charge separation from the formation of a heterostructure interface with reduced defects, resulting in a sufficient photovoltage for self-driving. To construct self-driven and sustainable overall cells without an external potential and considerable reduction in transparency, two-electrode PEC cells with a G-SnTiO photoanode and Cu2O photocathode were fabricated with a regular hexahedron shape for a color degradation test of methylene-blue-incorporated electrolytes, and exhibited enhanced purification speed and robust durability.
关键词： Charge transport,Photoelectrochemistry,Water oxidation,Compositionally graded structure,Self-driven overall cell
更新于2025-09-23 15:21:01
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<i>In situ</i> growth of α-Fe <sub/>2</sub> O <sub/>3</sub> @Co <sub/>3</sub> O <sub/>4</sub> core–shell wormlike nanoarrays for a highly efficient photoelectrochemical water oxidation reaction
摘要： Photoelectrochemical (PEC) water splitting represents a promising strategy to convert solar energy into chemical energy in the form of hydrogen, but its performance is severely limited by the sluggish water oxidation reaction. Herein, for the first time, we report the direct assembly of an ultrathin, uniform, and dense layer of Co3O4 on wormlike nanostructured hematite (WN-α-Fe2O3) to form a large-area and high-density WN-α-Fe2O3@Co3O4 core–shell nanoarray via in situ hydrothermal growth followed by calcination, in which the electrostatic force between WN-α-Fe2O3 and the reactants, pH- and temperature-controlled structures of WN-α-Fe2O3, and ultralow nucleation rate of Co3O4 precursors all play critical roles. The obtained heteronanostructure array shows a photocurrent density of 3.48 mA cm?2, which is 4.05 times higher than that of pristine WN-α-Fe2O3 (0.86 mA cm?2), an onset potential of ～0.62 V, 60 mV lower than that of α-Fe2O3 (～0.68 V), and a photoconversion efficiency of 0.55%, 3.93 times higher than that of WN-α-Fe2O3 (0.14%). This is among the highest performances reported for Fe2O3-based photoanodes for water splitting. It is discovered that the Co3O4 shells can significantly enhance the charge separation, accelerate the charge transport and transfer, and reduce the charge transfer resistance from the photoelectrode to the electrolyte for a fast water oxidation reaction, thereby greatly promoting the PEC water oxidation performance of pristine WN-α-Fe2O3. This work not only creates a novel low-cost and Earth-abundant WN-α-Fe2O3@Co3O4 photoelectrode with superior PEC water oxidation performance and provides scientific insights into the enhancement mechanism, but also offers a general strategy for the in situ growth of water oxidation catalysts on various photoelectrodes with 3-D complex geometries for PEC water splitting.
关键词： α-Fe2O3,water oxidation reaction,Co3O4,Photoelectrochemical water splitting,core–shell nanoarray
更新于2025-09-23 15:19:57
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Bio-template assisted hierarchical ZnO superstructures coupled with graphene quantum dots for enhanced water oxidation kinetics
摘要： Due to anisotropic growth behavior and tunable electrical properties, ZnO nanostructures having dimensions such as 0-D, 1-D, 2-D and 3-D are actively studied for their optoelectronic properties. However, ZnO based photoanodes suffer from unfavorable recombination of electron hole pair, which hinders its use in photoelectrochemical (PEC) water oxidation. Herein, we demonstrate a strategy to enhance the PEC performance using bio-template assisted in-situ grown hierarchical ZnO superstructures directly over fluorine-doped tin oxide (FTO) modified by graphene quantum dots (GQDs). GQDs decorated hierarchical ZnO superstructures displayed a significant increment of ~77% in photocurrent density value compared to pristine ZnO with an impressive carrier density of 3.19 × 1020 cm?3, which is ~1.8 orders of magnitude higher than that of pristine ZnO. It is observed that GQDs acts as an efficient hole extractor, which improves the carrier separation on ZnO surface and reduces the hole trapping probability.
关键词： Hole extracting agent,Polygalacturonic acid,Hierarchical ZnO superstructures,Photoelectrochemical water oxidation,Graphene quantum dots
更新于2025-09-23 15:19:57